1. Field of the Invention
The present invention relates to an image monitoring apparatus for detecting a moving object, such as an illegal trespasser, from image information obtained by picking up an area to be monitored and, more particularly, to an apparatus for combining dispersed images of a moving object extracted from an image.
2. Description of the Related Art
In a security system, for example, an image monitoring apparatus for picking up an area to be monitored by a television camera and detecting an illegal trespasser or the like from information of the picked-up image has been developed.
In such an image monitoring apparatus, in order to detect, e.g., an illegal trespasser, change information of an image obtained when an illegal trespasser moves in an image is extracted. In order to extract the change image, images separated by time intervals in a picked-up area to be monitored are subjected to subtraction to remove a stationary portion, thereby extracting only a change region (moving object).
That is, under the assumption that a one-to-one correspondence is present between a picked-up moving object and a change region extracted by subtraction, a moving object can be determined by extracting a change region.
In the same area to be monitored, however, shadow positions of a picked-up image are different between a fine day and a rainy day, and between in the morning and the evening. Therefore, if these shadow portions are processed as moving objects, movement of a real moving object cannot be correctly detected.
A change region in an image corresponding to a moving object is mostly dispersed and extracted in the image in accordance with a moving direction of the moving object in an area to be monitored, a fetching time interval of a picked-up image, or the like. In many cases, therefore, the shape of the picked-up moving object cannot be directly extracted.
Especially when a moving object is accompanied with a shadow region by sunshine or intense illumination, it is difficult to separately extract the moving object and the shadow region.